1
|
Sakowski SA, Koubek EJ, Chen KS, Goutman SA, Feldman EL. Role of the Exposome in Neurodegenerative Disease: Recent Insights and Future Directions. Ann Neurol 2024; 95:635-652. [PMID: 38411261 PMCID: PMC11023772 DOI: 10.1002/ana.26897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 02/02/2024] [Accepted: 02/05/2024] [Indexed: 02/28/2024]
Abstract
Neurodegenerative diseases are increasing in prevalence and place a significant burden on society. The causes are multifactorial and complex, and increasing evidence suggests a dynamic interplay between genes and the environment, emphasizing the importance of identifying and understanding the role of lifelong exposures, known as the exposome, on the nervous system. This review provides an overview of recent advances toward defining neurodegenerative disease exposomes, focusing on Parkinson's disease, amyotrophic lateral sclerosis, and Alzheimer's disease. We present the current state of the field based on emerging data, elaborate on key themes and potential mechanisms, and conclude with limitations and future directions. ANN NEUROL 2024;95:635-652.
Collapse
Affiliation(s)
- Stacey A. Sakowski
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI 48109, USA
| | - Emily J. Koubek
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kevin S. Chen
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Stephen A. Goutman
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI 48109, USA
| | - Eva L. Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI 48109, USA
| |
Collapse
|
2
|
Guo K, Figueroa-Romero C, Noureldein M, Hinder LM, Sakowski SA, Rumora AE, Petit H, Savelieff MG, Hur J, Feldman EL. Gut microbiota in a mouse model of obesity and peripheral neuropathy associated with plasma and nerve lipidomics and nerve transcriptomics. Microbiome 2023; 11:52. [PMID: 36922895 PMCID: PMC10015923 DOI: 10.1186/s40168-022-01436-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 11/25/2022] [Indexed: 06/18/2023]
Abstract
BACKGROUND Peripheral neuropathy (PN) is a common complication in obesity, prediabetes, and type 2 diabetes, though its pathogenesis remains incompletely understood. In a murine high-fat diet (HFD) obesity model of PN, dietary reversal (HFD-R) to a low-fat standard diet (SD) restores nerve function and the nerve lipidome to normal. As the gut microbiome represents a potential link between dietary fat intake and nerve health, the current study assessed shifts in microbiome community structure by 16S rRNA profiling during the paradigm of dietary reversal (HFD-R) in various gut niches. Dietary fat content (HFD versus SD) was also correlated to gut flora and metabolic and PN phenotypes. Finally, PN-associated microbial taxa that correlated with the plasma and sciatic nerve lipidome and nerve transcriptome were used to identify lipid species and genes intimately related to PN phenotypes. RESULTS Microbiome structure was altered in HFD relative to SD but rapidly reversed with HFD-R. Specific taxa variants correlating positively with metabolic health associated inversely with PN, while specific taxa negatively linked to metabolic health positively associated with PN. In HFD, PN-associated taxa variants, including Lactobacillus, Lachnoclostridium, and Anaerotruncus, also positively correlated with several lipid species, especially elevated plasma sphingomyelins and sciatic nerve triglycerides. Negative correlations were additionally present with other taxa variants. Moreover, relationships that emerged between specific PN-associated taxa variants and the sciatic nerve transcriptome were related to inflammation, lipid metabolism, and antioxidant defense pathways, which are all established in PN pathogenesis. CONCLUSIONS The current results indicate that microbiome structure is altered with HFD, and that certain taxa variants correlate with metabolic health and PN. Apparent links between PN-associated taxa and certain lipid species and nerve transcriptome-related pathways additionally provide insight into new targets for microbiota and the associated underlying mechanisms of action in PN. Thus, these findings strengthen the possibility of a gut-microbiome-peripheral nervous system signature in PN and support continuing studies focused on defining the connection between the gut microbiome and nerve health to inform mechanistic insight and therapeutic opportunities. Video Abstract.
Collapse
Affiliation(s)
- Kai Guo
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| | | | - Mohamed Noureldein
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| | - Lucy M. Hinder
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
- Reata Pharmaceuticals, Irving, TX 75063 USA
| | - Stacey A. Sakowski
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| | - Amy E. Rumora
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
- Department of Neurology, Columbia University, New York, NY 10032 USA
| | - Hayley Petit
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| | - Masha G. Savelieff
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| | - Junguk Hur
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58202 USA
| | - Eva L. Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| |
Collapse
|
3
|
Sakowski SA, Savelieff MG, Feldman EL. Disrupted axon-glia communication leads to neurodegeneration in metabolic diseases. Neurobiol Dis 2023; 177:105994. [PMID: 36632920 DOI: 10.1016/j.nbd.2023.105994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Affiliation(s)
- Stacey A Sakowski
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI 48109, USA
| | - Masha G Savelieff
- Department of Biomedical Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI 48109, USA.
| |
Collapse
|
4
|
Goutman SA, Guo K, Savelieff MG, Patterson A, Sakowski SA, Habra H, Karnovsky A, Hur J, Feldman EL. Metabolomics identifies shared lipid pathways in independent amyotrophic lateral sclerosis cohorts. Brain 2022; 145:4425-4439. [PMID: 35088843 PMCID: PMC9762943 DOI: 10.1093/brain/awac025] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 11/22/2021] [Accepted: 01/05/2022] [Indexed: 11/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease lacking effective treatments. This is due, in part, to a complex and incompletely understood pathophysiology. To shed light, we conducted untargeted metabolomics on plasma from two independent cross-sectional ALS cohorts versus control participants to identify recurrent dysregulated metabolic pathways. Untargeted metabolomics was performed on plasma from two ALS cohorts (cohort 1, n = 125; cohort 2, n = 225) and healthy controls (cohort 1, n = 71; cohort 2, n = 104). Individual differential metabolites in ALS cases versus controls were assessed by Wilcoxon, adjusted logistic regression and partial least squares-discriminant analysis, while group lasso explored sub-pathway level differences. Adjustment parameters included age, sex and body mass index. Metabolomics pathway enrichment analysis was performed on metabolites selected using the above methods. Additionally, we conducted a sex sensitivity analysis due to sex imbalance in the cohort 2 control arm. Finally, a data-driven approach, differential network enrichment analysis (DNEA), was performed on a combined dataset to further identify important ALS metabolic pathways. Cohort 2 ALS participants were slightly older than the controls (64.0 versus 62.0 years, P = 0.009). Cohort 2 controls were over-represented in females (68%, P < 0.001). The most concordant cohort 1 and 2 pathways centred heavily on lipid sub-pathways, including complex and signalling lipid species and metabolic intermediates. There were differences in sub-pathways that were enriched in ALS females versus males, including in lipid sub-pathways. Finally, DNEA of the merged metabolite dataset of both ALS and control cohorts identified nine significant subnetworks; three centred on lipids and two encompassed a range of sub-pathways. In our analysis, we saw consistent and important shared metabolic sub-pathways in both ALS cohorts, particularly in lipids, further supporting their importance as ALS pathomechanisms and therapeutics targets.
Collapse
Affiliation(s)
- Stephen A Goutman
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, USA
| | - Kai Guo
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, USA
| | - Masha G Savelieff
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, USA
| | - Adam Patterson
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, USA
| | - Stacey A Sakowski
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, USA
| | - Hani Habra
- Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Alla Karnovsky
- Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Junguk Hur
- Department of Biomedical Sciences, University of North Dakota, Grand Forks, ND, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, USA
| |
Collapse
|
5
|
Sakowski SA, Chen KS. Stem cell therapy for central nervous system disorders: Metabolic interactions between transplanted cells and local microenvironments. Neurobiol Dis 2022; 173:105842. [PMID: 35988874 PMCID: PMC10117179 DOI: 10.1016/j.nbd.2022.105842] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 08/12/2022] [Accepted: 08/15/2022] [Indexed: 10/15/2022] Open
Abstract
Stem cell therapy is a promising and rapidly advancing treatment strategy for a multitude of neurologic disorders. Yet, while early phase clinical trials are being pursued in many disorders, the mechanism of action often remains unclear. One important potential mechanism by which stem cells provide neuroprotection is through metabolic signaling with diseased neurons, glia, and other cell types in the nervous system microenvironment. Early studies exploring such interactions report normalization of glucose metabolism, induction of protective mitochondrial genes, and even interactions with supportive neurovasculature. Local metabolic conditions also impact stem cell biology, which can have a large impact on transplant viability and efficacy. Epigenetic changes that occur in the donor prior to collection of stem cells, and even during in vitro culture conditions, may have effects on stem cell biology that are carried into the host upon stem cell transplantation. Transplanted stem cells also face potentially toxic metabolic microenvironments at the targeted transplant site. Novel approaches for metabolically "preconditioning" stem cells prior to transplant harness metabolic machinery to optimize stem cell survival upon transplant. Ultimately, an improved understanding of the metabolic cross-talk between implanted stem cells and the local nervous system environment, in both disease and injury states, will increase the likelihood of success in translating stem cell therapy to early trials in neurological disease.
Collapse
Affiliation(s)
- Stacey A Sakowski
- Department of Neurology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
| | - Kevin S Chen
- Department of Neurology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA; Department of Neurosurgery, University of Michigan, 1500 E. Medical Center Dr, Ann Arbor, MI 48109, USA.
| |
Collapse
|
6
|
Lo TW, Figueroa-Romero C, Hur J, Pacut C, Stoll E, Spring C, Lewis R, Nair A, Goutman SA, Sakowski SA, Nagrath S, Feldman EL. Extracellular Vesicles in Serum and Central Nervous System Tissues Contain microRNA Signatures in Sporadic Amyotrophic Lateral Sclerosis. Front Mol Neurosci 2021; 14:739016. [PMID: 34776863 PMCID: PMC8586523 DOI: 10.3389/fnmol.2021.739016] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 10/01/2021] [Indexed: 01/12/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a terminalneurodegenerative disease. Clinical and molecular observations suggest that ALS pathology originates at a single site and spreads in an organized and prion-like manner, possibly driven by extracellular vesicles. Extracellular vesicles (EVs) transfer cargo molecules associated with ALS pathogenesis, such as misfolded and aggregated proteins and dysregulated microRNAs (miRNAs). However, it is poorly understood whether altered levels of circulating extracellular vesicles or their cargo components reflect pathological signatures of the disease. In this study, we used immuno-affinity-based microfluidic technology, electron microscopy, and NanoString miRNA profiling to isolate and characterize extracellular vesicles and their miRNA cargo from frontal cortex, spinal cord, and serum of sporadic ALS (n = 15) and healthy control (n = 16) participants. We found larger extracellular vesicles in ALS spinal cord versus controls and smaller sized vesicles in ALS serum. However, there were no changes in the number of extracellular vesicles between cases and controls across any tissues. Characterization of extracellular vesicle-derived miRNA cargo in ALS compared to controls identified significantly altered miRNA levels in all tissues; miRNAs were reduced in ALS frontal cortex and spinal cord and increased in serum. Two miRNAs were dysregulated in all three tissues: miR-342-3p was increased in ALS, and miR-1254 was reduced in ALS. Additional miRNAs overlapping across two tissues included miR-587, miR-298, miR-4443, and miR-450a-2-3p. Predicted targets and pathways associated with the dysregulated miRNAs across the ALS tissues were associated with common biological pathways altered in neurodegeneration, including axon guidance and long-term potentiation. A predicted target of one identified miRNA (N-deacetylase and N-sulfotransferase 4; NDST4) was likewise dysregulated in an in vitro model of ALS, verifying potential biological relevance. Together, these findings demonstrate that circulating extracellular vesicle miRNA cargo mirror those of the central nervous system disease state in ALS, and thereby offer insight into possible pathogenic factors and diagnostic opportunities.
Collapse
Affiliation(s)
- Ting-wen Lo
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, United States
| | | | - Junguk Hur
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States
| | - Crystal Pacut
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Evan Stoll
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Calvin Spring
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Rose Lewis
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Athul Nair
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Stephen A. Goutman
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Stacey A. Sakowski
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Sunitha Nagrath
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, United States
- Binterface Institute, University of Michigan, Ann Arbor, MI, United States
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI, United States
| | - Eva L. Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| |
Collapse
|
7
|
De Marchi F, Munitic I, Amedei A, Berry JD, Feldman EL, Aronica E, Nardo G, Van Weehaeghe D, Niccolai E, Prtenjaca N, Sakowski SA, Bendotti C, Mazzini L. Interplay between immunity and amyotrophic lateral sclerosis: Clinical impact. Neurosci Biobehav Rev 2021; 127:958-978. [PMID: 34153344 PMCID: PMC8428677 DOI: 10.1016/j.neubiorev.2021.06.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/07/2021] [Accepted: 06/17/2021] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a debilitating and rapidly fatal neurodegenerative disease. Despite decades of research and many new insights into disease biology over the 150 years since the disease was first described, causative pathogenic mechanisms in ALS remain poorly understood, especially in sporadic cases. Our understanding of the role of the immune system in ALS pathophysiology, however, is rapidly expanding. The aim of this manuscript is to summarize the recent advances regarding the immune system involvement in ALS, with particular attention to clinical translation. We focus on the potential pathophysiologic mechanism of the immune system in ALS, discussing local and systemic factors (blood, cerebrospinal fluid, and microbiota) that influence ALS onset and progression in animal models and people. We also explore the potential of Positron Emission Tomography to detect neuroinflammation in vivo, and discuss ongoing clinical trials of therapies targeting the immune system. With validation in human patients, new evidence in this emerging field will serve to identify novel therapeutic targets and provide realistic hope for personalized treatment strategies.
Collapse
Affiliation(s)
- Fabiola De Marchi
- Department of Neurology and ALS Centre, University of Piemonte Orientale, Maggiore Della Carità Hospital, Corso Mazzini 18, Novara, 28100, Italy
| | - Ivana Munitic
- Laboratory for Molecular Immunology, Department of Biotechnology, University of Rijeka, R. Matejcic 2, 51000, Rijeka, Croatia
| | - Amedeo Amedei
- Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
| | - James D Berry
- Sean M. Healey & AMG Center for ALS, Department of Neurology, Massachusetts General Hospital, 165 Cambridge Street, Suite 600, Boston, MA, 02114, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Eleonora Aronica
- Amsterdam UMC, University of Amsterdam, Department of (Neuro) Pathology, Amsterdam Neuroscience, Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands
| | - Giovanni Nardo
- Laboratory of Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, Milanm, 20156, Italy
| | - Donatienne Van Weehaeghe
- Division of Nuclear Medicine, Department of Imaging and Pathology, University Hospitals Leuven, KU Leuven, Leuven, Belgium
| | - Elena Niccolai
- Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
| | - Nikolina Prtenjaca
- Laboratory for Molecular Immunology, Department of Biotechnology, University of Rijeka, R. Matejcic 2, 51000, Rijeka, Croatia
| | - Stacey A Sakowski
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Caterina Bendotti
- Laboratory of Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, Milanm, 20156, Italy
| | - Letizia Mazzini
- Department of Neurology and ALS Centre, University of Piemonte Orientale, Maggiore Della Carità Hospital, Corso Mazzini 18, Novara, 28100, Italy.
| |
Collapse
|
8
|
McGinley LM, Willsey MS, Kashlan ON, Chen KS, Hayes JM, Bergin IL, Mason SN, Stebbins AW, Kwentus JF, Pacut C, Kollmer J, Sakowski SA, Bell CB, Chestek CA, Murphy GG, Patil PG, Feldman EL. Magnetic resonance imaging of human neural stem cells in rodent and primate brain. Stem Cells Transl Med 2020; 10:83-97. [PMID: 32841522 PMCID: PMC7780819 DOI: 10.1002/sctm.20-0126] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 07/03/2020] [Accepted: 07/27/2020] [Indexed: 12/11/2022] Open
Abstract
Stem cell transplantation therapies are currently under investigation for central nervous system disorders. Although preclinical models show benefit, clinical translation is somewhat limited by the absence of reliable noninvasive methods to confirm targeting and monitor transplanted cells in vivo. Here, we assess a novel magnetic resonance imaging (MRI) contrast agent derived from magnetotactic bacteria, magneto‐endosymbionts (MEs), as a translatable methodology for in vivo tracking of stem cells after intracranial transplantation. We show that ME labeling provides robust MRI contrast without impairment of cell viability or other important therapeutic features. Labeled cells were visualized immediately post‐transplantation and over time by serial MRI in nonhuman primate and mouse brain. Postmortem tissue analysis confirmed on‐target grft location, and linear correlations were observed between MRI signal, cell engraftment, and tissue ME levels, suggesting that MEs may be useful for determining graft survival or rejection. Overall, these findings indicate that MEs are an effective tool for in vivo tracking and monitoring of cell transplantation therapies with potential relevance to many cellular therapy applications.
Collapse
Affiliation(s)
- Lisa M McGinley
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Matthew S Willsey
- Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Osama N Kashlan
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA.,Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA
| | - Kevin S Chen
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA.,Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA
| | - John M Hayes
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Ingrid L Bergin
- Unit for Laboratory Animal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Shayna N Mason
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Aaron W Stebbins
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Crystal Pacut
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jennifer Kollmer
- Department of Neuroradiology, University Hospital Heidelberg, Heidelberg, Germany
| | - Stacey A Sakowski
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Caleb B Bell
- Bell Biosystems, San Francisco, California, USA.,G4S Capital & Ikigai Accelerator, Santa Clara, California, USA
| | - Cynthia A Chestek
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.,Department of Electrical Engineering, University of Michigan, Ann Arbor, Michigan, USA.,Neuroscience and Robotics Graduate Program, University of Michigan, Ann Arbor, Michigan, USA
| | - Geoffrey G Murphy
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA.,Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Parag G Patil
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA.,Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| |
Collapse
|
9
|
Paez-Colasante X, Figueroa-Romero C, Rumora AE, Hur J, Mendelson FE, Hayes JM, Backus C, Taubman GF, Heinicke L, Walter NG, Barmada SJ, Sakowski SA, Feldman EL. Cytoplasmic TDP43 Binds microRNAs: New Disease Targets in Amyotrophic Lateral Sclerosis. Front Cell Neurosci 2020; 14:117. [PMID: 32477070 PMCID: PMC7235295 DOI: 10.3389/fncel.2020.00117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/14/2020] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive, fatal, and incurable neurodegenerative disease. Recent studies suggest that dysregulation of gene expression by microRNAs (miRNAs) may play an important role in ALS pathogenesis. The reversible nature of this dysregulation makes miRNAs attractive pharmacological targets and a potential therapeutic avenue. Under physiological conditions, miRNA biogenesis, which begins in the nucleus and includes further maturation in the cytoplasm, involves trans-activation response element DNA/RNA-binding protein of 43 kDa (TDP43). However, TDP43 mutations or stress trigger TDP43 mislocalization and inclusion formation, a hallmark of most ALS cases, that may lead to aberrant protein/miRNA interactions in the cytoplasm. Herein, we demonstrated that TDP43 exhibits differential binding affinity for select miRNAs, which prompted us to profile miRNAs that preferentially bind cytoplasmic TDP43. Using cellular models expressing TDP43 variants and miRNA profiling analyses, we identified differential levels of 65 cytoplasmic TDP43-associated miRNAs. Of these, approximately 30% exhibited levels that differed by more than 3-fold in the cytoplasmic TDP43 models relative to our control model. The hits included both novel miRNAs and miRNAs previously associated with ALS that potentially regulate several predicted genes and pathways that may be important for pathogenesis. Accordingly, these findings highlight specific miRNAs that may shed light on relevant disease pathways and could represent potential biomarkers and reversible treatment targets for ALS.
Collapse
Affiliation(s)
| | | | - Amy E. Rumora
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Junguk Hur
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States
| | - Faye E. Mendelson
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - John M. Hayes
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Carey Backus
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | | | - Laurie Heinicke
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI, United States
| | - Nils G. Walter
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI, United States
| | - Sami J. Barmada
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Stacey A. Sakowski
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Eva L. Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| |
Collapse
|
10
|
Sakowski SA, Feldman EL, Jagsi R, Singer K. Energizing the Conversation: How to Identify and Overcome Gender Inequalities in Academic Medicine. J Contin Educ Health Prof 2020; 40:274-278. [PMID: 33284179 PMCID: PMC8328536 DOI: 10.1097/ceh.0000000000000296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Gender inequality exists in advanced faculty and leadership positions at academic medical centers; however, despite growing awareness, how to best approach and rectify the issue is unknown. To energize the conversation on gender inequality at one academic medical center, chairs and women faculty were surveyed to identify barriers faced by women navigating their careers. A symposium with short talks to increase awareness, a panel with University leaders to discuss issues and successful strategies to overcome gaps, and focus groups to delve further into key areas that underlie inequity through an active café style format were planned and implemented. This multifaceted approach resulted in a wealth of knowledge. The symposium and panel highlighted important relevant issues and offered personal strategies for successful career advancement, while the focus group discussions further identified barriers and inspired ongoing efforts across departments and novel approaches to overcome three key issues (work-life integration, deliberate promotion of mentor/sponsor relationships, and overcoming unconscious bias) identified through the initial surveys. Compiled data were then disseminated to participants and University leaders to enhance awareness of available programs and prompt action in critical areas lacking support. Overall, the approach indicated that securing support from leaders and the academic community alike are pertinent to emphasize actions needed to overcome issues affecting women in academic medicine. Moreover, bringing leaders and faculty together for an informational session and brainstorming appears to energize the conversation. Such efforts can ultimately instill change and establish an inclusive environment where all members of the academic medicine community can thrive.
Collapse
Affiliation(s)
| | - Eva L. Feldman
- Department of Neurology, University of Michigan, Ann Arbor, Michigan
| | - Reshma Jagsi
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan
- Center for Bioethics and Social Sciences in Medicine, University of Michigan, Ann Arbor, Michigan
| | | |
Collapse
|
11
|
Goutman SA, Savelieff MG, Sakowski SA, Feldman EL. Stem cell treatments for amyotrophic lateral sclerosis: a critical overview of early phase trials. Expert Opin Investig Drugs 2019; 28:525-543. [PMID: 31189354 DOI: 10.1080/13543784.2019.1627324] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of cortical, brainstem, and spinal motor neurons; it causes progressive muscle weakness and atrophy, respiratory failure, and death. No currently available treatment either stops or reverses this disease. Therapeutics to slow, stop, and reverse ALS are needed. Stem cells may be a viable solution to sustain and nurture diseased motor neurons. Several early-stage clinical trials have been launched to assess the potential of stem cells for ALS treatment. Areas covered: Expert opinion: AREAS COVERED This review covers the key advances from early phase clinical trials of stem cell therapy for ALS and identifies promising avenues and key challenges. EXPERT OPINION Clinical trials in humans are still in the nascent stages of development. It will be critical to ensure that powered, well-controlled trials are conducted, that optimal treatment windows are identified, and that the ideal cell type, cell dose, and delivery site and method are determined. Several trials have used more invasive procedures, and ethical concerns of sham procedures on patients in the control arm and on their safety should be considered.
Collapse
Affiliation(s)
- Stephen A Goutman
- a Department of Neurology , University of Michigan , Ann Arbor , MI , USA.,b Program for Neurology Research & Discovery , University of Michigan , Ann Arbor , MI , USA
| | - Masha G Savelieff
- a Department of Neurology , University of Michigan , Ann Arbor , MI , USA.,b Program for Neurology Research & Discovery , University of Michigan , Ann Arbor , MI , USA
| | - Stacey A Sakowski
- a Department of Neurology , University of Michigan , Ann Arbor , MI , USA.,b Program for Neurology Research & Discovery , University of Michigan , Ann Arbor , MI , USA
| | - Eva L Feldman
- a Department of Neurology , University of Michigan , Ann Arbor , MI , USA.,b Program for Neurology Research & Discovery , University of Michigan , Ann Arbor , MI , USA
| |
Collapse
|
12
|
Rumora AE, Savelieff MG, Sakowski SA, Feldman EL. Disorders of mitochondrial dynamics in peripheral neuropathy: Clues from hereditary neuropathy and diabetes. Int Rev Neurobiol 2019; 145:127-176. [PMID: 31208522 DOI: 10.1016/bs.irn.2019.05.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Peripheral neuropathy is a common and debilitating complication of diabetes and prediabetes. Recent clinical studies have identified an association between the development of neuropathy and dyslipidemia in prediabetic and diabetic patients. Despite the prevalence of this complication, studies identifying molecular mechanisms that underlie neuropathy progression in prediabetes or diabetes are limited. However, dysfunctional mitochondrial pathways in hereditary neuropathy provide feasible molecular targets for assessing mitochondrial dysfunction in neuropathy associated with prediabetes or diabetes. Recent studies suggest that elevated levels of dietary saturated fatty acids (SFAs) associated with dyslipidemia impair mitochondrial dynamics in sensory neurons by inducing mitochondrial depolarization, compromising mitochondrial bioenergetics, and impairing axonal mitochondrial transport. This causes lower neuronal ATP and apoptosis. Conversely, monounsaturated fatty acids (MUFAs) restore nerve and sensory mitochondrial function. Understanding the mitochondrial pathways that contribute to neuropathy progression in prediabetes and diabetes may provide therapeutic targets for the treatment of this debilitating complication.
Collapse
Affiliation(s)
- Amy E Rumora
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Masha G Savelieff
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Stacey A Sakowski
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States.
| |
Collapse
|
13
|
Chen KS, McGinley LM, Kashlan ON, Hayes JM, Bruno ES, Chang JS, Mendelson FE, Tabbey MA, Johe K, Sakowski SA, Feldman EL. Targeted intraspinal injections to assess therapies in rodent models of neurological disorders. Nat Protoc 2019; 14:331-349. [PMID: 30610242 DOI: 10.1038/s41596-018-0095-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Despite decades of research, pharmacological therapies for spinal cord motor pathologies are limited. Alternatives using macromolecular, viral, or cell-based therapies show early promise. However, introducing these substances into the spinal cord, past the blood-brain barrier, without causing injury is challenging. We describe a technique for intraspinal injection targeting the lumbar ventral horn in rodents. This technique preserves motor performance and has a proven track record of translation into phase 1 and 2 clinical trials in amyotrophic lateral sclerosis (ALS) patients. The procedure, in brief, involves exposure of the thoracolumbar spine and dissection of paraspinous muscles over the target vertebrae. Following laminectomy, the spine is affixed to a stereotactic frame, permitting precise and reproducible injection throughout the lumbar spine. We have used this protocol to inject various stem cell types, primarily human spinal stem cells (HSSCs); however, the injection is adaptable to any candidate therapeutic cell, virus, or macromolecule product. In addition to a detailed procedure, we provide stereotactic coordinates that assist in targeting of the lumbar spine and instructional videos. The protocol takes ~2 h per animal.
Collapse
Affiliation(s)
- Kevin S Chen
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA
| | - Lisa M McGinley
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Osama N Kashlan
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA
| | - John M Hayes
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | | | - Josh S Chang
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Faye E Mendelson
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Maegan A Tabbey
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | | | | | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA.
| |
Collapse
|
14
|
Goutman SA, Brown MB, Glass JD, Boulis NM, Johe K, Hazel T, Cudkowicz M, Atassi N, Borges L, Patil PG, Sakowski SA, Feldman EL. Long-term Phase 1/2 intraspinal stem cell transplantation outcomes in ALS. Ann Clin Transl Neurol 2018; 5:730-740. [PMID: 29928656 PMCID: PMC5989736 DOI: 10.1002/acn3.567] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 03/25/2018] [Indexed: 12/12/2022] Open
Abstract
Objective Intraspinal human spinal cord‐derived neural stem cell (HSSC) transplantation is a potential therapy for amyotrophic lateral sclerosis (ALS); however, previous trials lack controls. This post hoc analysis compared ambulatory limb‐onset ALS participants in Phase 1 and 2 (Ph1/2) open‐label intraspinal HSSC transplantation studies up to 3 years after transplant to matched participants in Pooled Resource Open‐Access ALS Clinical Trials (PRO‐ACT) and ceftriaxone datasets to provide required analyses to inform future clinical trial designs. Methods Survival, ALSFRS‐R, and a composite statistic (ALS/SURV) combining survival and ALS Functional Rating Scale revised (ALSFRS‐R) functional status were assessed for matched participant subsets: PRO‐ACT n = 1108, Ph1/2 n = 21 and ceftriaxone n = 177, Ph1/2 n = 20. Results Survival did not differ significantly between cohorts: Ph1/2 median survival 4.7 years, 95% CI (1.2, ∞) versus PRO‐ACT 2.3 years (1.9, 2.5), P = 1.0; Ph1/2 3.0 years (1.2, 5.6) versus ceftriaxone 2.3 years (1.8, 2.8), P = 0.88. Mean ALSFRS‐R at 24 months significantly differed between Ph1/2 and both comparison cohorts (Ph1/2 30.1 ± 8.6 vs. PRO‐ACT 24.0 ± 10.2, P = 0.048; Ph1/2 30.7 ± 8.8 vs. ceftriaxone 19.2 ± 9.5, P = 0.0023). Using ALS/SURV, median PRO‐ACT and ceftriaxone participants died by 24 months, whereas median Ph1/2 participant ALSFRS‐Rs were 23 (P = 0.0038) and 19 (P = 0.14) in PRO‐ACT and ceftriaxone comparisons at 24 months, respectively, supporting improved functional outcomes in the Ph1/2 study. Interpretation Comparison of Ph1/2 studies to historical datasets revealed significantly improved survival and function using ALS/SURV versus PRO‐ACT controls. While results are encouraging, comparison against historical populations demonstrate limitations in noncontrolled studies. These findings support continued evaluation of HSSC transplantation in ALS, support the benefit of control populations, and enable necessary power calculations to design a randomized, sham surgery‐controlled efficacy study.
Collapse
Affiliation(s)
- Stephen A Goutman
- Department of Neurology University of Michigan 109 Zina Pitcher Place 5017 AAT-BSRB Ann Arbor Michigan 48109
| | - Morton B Brown
- Department of Biostatistics University of Michigan 1415 Washington Heights M4039 SPH II Ann Arbor Michigan 48109
| | - Jonathan D Glass
- Department of Neurology Emory University School of Medicine 101 Woodruff Circle Atlanta Georgia 30322
| | - Nicholas M Boulis
- Department of Neurosurgery Emory University School of Medicine 101 Woodruff Circle WMB Room 6309 Atlanta Georgia
| | - Karl Johe
- Neuralstem, Inc. 20271 Goldenrod Lane Suite 2033 Germantown Maryland 20876
| | - Tom Hazel
- Neuralstem, Inc. 20271 Goldenrod Lane Suite 2033 Germantown Maryland 20876
| | - Merit Cudkowicz
- Department of Neurology Massachusetts General Hospital Harvard Medical School 165 Cambridge Street Boston Massachusetts 02114
| | - Nazem Atassi
- Department of Neurology Massachusetts General Hospital Harvard Medical School 165 Cambridge Street Boston Massachusetts 02114
| | - Lawrence Borges
- Department of Neurosurgery Massachusetts General Hospital Harvard Medical School 15 Parkman Street Wand ACC 745 Boston Massachusetts 02114
| | - Parag G Patil
- Department of Neurology University of Michigan 109 Zina Pitcher Place 5017 AAT-BSRB Ann Arbor Michigan 48109.,Department of Neurosurgery University of Michigan 1500 E. Medical Center Drive SPC 5338 Ann Arbor Michigan 48109
| | - Stacey A Sakowski
- Program for Neurology Research and Discovery University of Michigan 109 Zina Pitcher Place 5017 AAT-BSRB Ann Arbor Michigan 48109
| | - Eva L Feldman
- Department of Neurology University of Michigan 109 Zina Pitcher Place 5017 AAT-BSRB Ann Arbor Michigan 48109.,Program for Neurology Research and Discovery University of Michigan 109 Zina Pitcher Place 5017 AAT-BSRB Ann Arbor Michigan 48109
| |
Collapse
|
15
|
O’Brien PD, Hinder LM, Parlee SD, Hayes JM, Backus C, Zhang H, Ma L, Sakowski SA, Brosius FC, Feldman EL. Dual CCR2/CCR5 antagonist treatment attenuates adipose inflammation, but not microvascular complications in ob/ob mice. Diabetes Obes Metab 2017; 19:1468-1472. [PMID: 28332276 PMCID: PMC5610585 DOI: 10.1111/dom.12950] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/13/2017] [Accepted: 03/19/2017] [Indexed: 12/31/2022]
Abstract
Diabetic peripheral neuropathy (DPN) and diabetic kidney disease (DKD) are common diabetic complications with limited treatment options. Experimental studies show that targeting inflammation using chemokine receptor (CCR) antagonists ameliorates DKD, presumably by reducing macrophage accumulation or activation. As inflammation is implicated in DPN development, we assessed whether CCR2 and CCR5 antagonism could also benefit DPN. Five-week-old ob/ob mice were fed a diet containing MK-0812, a dual CCR2-CCR5 receptor antagonist, for 8 weeks; DPN, DKD and metabolic phenotyping were then performed to determine the effect of CCR inhibition. Although MK-0812 reduced macrophage accumulation in adipose tissue, the treatment had largely no effect on metabolic parameters, nerve function or kidney disease in ob/ob mice. These results conflict with published data that demonstrate a benefit of CCR antagonists for DKD and hyperglycaemia. We conclude that CCR signaling blockade is ineffective in ob/ob mice and suspect that this is explained by the severe hyperglycaemia found in this model. It remains to be determined whether MK-0812 treatment, alone or in combination with improved glycaemic control, is useful in preventing diabetic complications in alternate animal models.
Collapse
Affiliation(s)
| | - Lucy M. Hinder
- Department of Neurology, University of Michigan, Ann Arbor, Michigan USA
| | - Sebastian D. Parlee
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, Michigan USA
| | - John M. Hayes
- Department of Neurology, University of Michigan, Ann Arbor, Michigan USA
| | - Carey Backus
- Department of Neurology, University of Michigan, Ann Arbor, Michigan USA
| | - Hongyu Zhang
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan USA
| | - Lijun Ma
- Department of Cardiometabolic Disease, Merck Research Laboratories, Kenilworth, New Jersey, USA
| | - Stacey A. Sakowski
- A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Frank C. Brosius
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan USA
| | - Eva L. Feldman
- Department of Neurology, University of Michigan, Ann Arbor, Michigan USA
| |
Collapse
|
16
|
Lunn JS, Sakowski SA, McGinley LM, Pacut C, Hazel TG, Johe K, Feldman EL. Autocrine production of IGF-I increases stem cell-mediated neuroprotection. Stem Cells 2016; 33:1480-9. [PMID: 25532472 DOI: 10.1002/stem.1933] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 12/01/2014] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder resulting in motor neuron (MN) loss. There are currently no effective therapies; however, cellular therapies using neural progenitor cells protect MNs and attenuate disease progression in G93A-SOD1 ALS rats. Recently, we completed a phase I clinical trial examining intraspinal human spinal stem cell (HSSC) transplantation in ALS patients which demonstrated our approach was safe and feasible, supporting the phase II trial currently in progress. In parallel, efforts focused on understanding the mechanisms underlying the preclinical benefit of HSSCs in vitro and in animal models of ALS led us to investigate how insulin-like growth factor-I (IGF-I) production contributes to cellular therapy neuroprotection. IGF-I is a potent growth factor with proven efficacy in preclinical ALS studies, and we contend that autocrine IGF-I production may enhance the salutary effects of HSSCs. By comparing the biological properties of HSSCs to HSSCs expressing sixfold higher levels of IGF-I, we demonstrate that IGF-I production augments the production of glial-derived neurotrophic factor and accelerates neurite outgrowth without adversely affecting HSSC proliferation or terminal differentiation. Furthermore, we demonstrate that increased IGF-I induces more potent MN protection from excitotoxicity via both indirect and direct mechanisms, as demonstrated using hanging inserts with primary MNs or by culturing with organotypic spinal cord slices, respectively. These findings support our theory that combining autocrine growth factor production with HSSC transplantation may offer a novel means to achieve additive neuroprotection in ALS.
Collapse
|
17
|
Chen KS, Sakowski SA, Feldman EL. Intraspinal stem cell transplantation for amyotrophic lateral sclerosis. Ann Neurol 2016; 79:342-53. [PMID: 26696091 DOI: 10.1002/ana.24584] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 12/18/2015] [Accepted: 12/18/2015] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder in which the loss of upper and lower motor neurons produces progressive weakness and eventually death. In the decades since the approval of riluzole, the only US Food and Drug Administration-approved medication to moderately slow progression of ALS, no new therapeutics have arisen to alter the course of the disease. This is partly due to our incomplete understanding of the complex pathogenesis of motor neuron degeneration. Stem cells have emerged as an attractive option in treating ALS, because they come armed with equally complex cellular machinery and may modulate the local microenvironment in many ways to rescue diseased motor neurons. Various stem cell types are being evaluated in preclinical and early clinical applications; here, we review the preclinical strategies and advances supporting the recent clinical translation of neural progenitor cell therapy for ALS. Specifically, we focus on the use of spinal cord neural progenitor cells and the pipeline starting from preclinical studies to the designs of phase I and IIa clinical trials involving direct intraspinal transplantation in humans.
Collapse
Affiliation(s)
- Kevin S Chen
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI
| | - Stacey A Sakowski
- A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, MI
| | - Eva L Feldman
- A. Alfred Taubman Medical Research Institute and Department of Neurology, University of Michigan, Ann Arbor, MI
| |
Collapse
|
18
|
McGinley LM, Sims E, Lunn JS, Kashlan ON, Chen KS, Bruno ES, Pacut CM, Hazel T, Johe K, Sakowski SA, Feldman EL. Human Cortical Neural Stem Cells Expressing Insulin-Like Growth Factor-I: A Novel Cellular Therapy for Alzheimer's Disease. Stem Cells Transl Med 2016; 5:379-91. [PMID: 26744412 PMCID: PMC4807660 DOI: 10.5966/sctm.2015-0103] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 11/19/2015] [Indexed: 01/05/2023] Open
Abstract
Alzheimer's disease (AD) is the most prevalent age-related neurodegenerative disorder and a leading cause of dementia. Current treatment fails to modify underlying disease pathologies and very little progress has been made to develop effective drug treatments. Cellular therapies impact disease by multiple mechanisms, providing increased efficacy compared with traditional single-target approaches. In amyotrophic lateral sclerosis, we have shown that transplanted spinal neural stem cells (NSCs) integrate into the spinal cord, form synapses with the host, improve inflammation, and reduce disease-associated pathologies. Our current goal is to develop a similar "best in class" cellular therapy for AD. Here, we characterize a novel human cortex-derived NSC line modified to express insulin-like growth factor-I (IGF-I), HK532-IGF-I. Because IGF-I promotes neurogenesis and synaptogenesis in vivo, this enhanced NSC line offers additional environmental enrichment, enhanced neuroprotection, and a multifaceted approach to treating complex AD pathologies. We show that autocrine IGF-I production does not impact the cell secretome or normal cellular functions, including proliferation, migration, or maintenance of progenitor status. However, HK532-IGF-I cells preferentially differentiate into gamma-aminobutyric acid-ergic neurons, a subtype dysregulated in AD; produce increased vascular endothelial growth factor levels; and display an increased neuroprotective capacity in vitro. We also demonstrate that HK532-IGF-I cells survive peri-hippocampal transplantation in a murine AD model and exhibit long-term persistence in targeted brain areas. In conclusion, we believe that harnessing the benefits of cellular and IGF-I therapies together will provide the optimal therapeutic benefit to patients, and our findings support further preclinical development of HK532-IGF-I cells into a disease-modifying intervention for AD.
Collapse
Affiliation(s)
- Lisa M McGinley
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Erika Sims
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - J Simon Lunn
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Osama N Kashlan
- Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA
| | - Kevin S Chen
- Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA
| | - Elizabeth S Bruno
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Crystal M Pacut
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Tom Hazel
- Neuralstem, Inc., Germantown, Maryland, USA
| | - Karl Johe
- Neuralstem, Inc., Germantown, Maryland, USA
| | - Stacey A Sakowski
- A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, Michigan, USA
| |
Collapse
|
19
|
O'Brien PD, Hur J, Robell NJ, Hayes JM, Sakowski SA, Feldman EL. Gender-specific differences in diabetic neuropathy in BTBR ob/ob mice. J Diabetes Complications 2016; 30:30-7. [PMID: 26525588 PMCID: PMC4698064 DOI: 10.1016/j.jdiacomp.2015.09.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 09/23/2015] [Accepted: 09/30/2015] [Indexed: 02/08/2023]
Abstract
AIMS To identify a female mouse model of diabetic peripheral neuropathy (DPN), we characterized DPN in female BTBR ob/ob mice and compared their phenotype to non-diabetic and gender-matched controls. We also identified dysregulated genes and pathways in sciatic nerve (SCN) and dorsal root ganglia (DRG) of female BTBR ob/ob mice to determine potential DPN mechanisms. METHODS Terminal neuropathy phenotyping consisted of examining latency to heat stimuli, sciatic motor and sural sensory nerve conduction velocities (NCV), and intraepidermal nerve fiber (IENF) density. For gene expression profiling, DRG and SCN were dissected, RNA was isolated and processed using microarray technology and differentially expressed genes were identified. RESULTS Similar motor and sensory NCV deficits were observed in male and female BTBR ob/ob mice at study termination; however, IENF density was greater in female ob/ob mice than their male counterparts. Male and female ob/ob mice exhibited similar weight gain, hyperglycemia, and hyperinsulinemia compared to non-diabetic controls, although triglycerides were elevated more so in males than in females. Transcriptional profiling of nerve tissue from female mice identified dysregulation of pathways related to inflammation. CONCLUSIONS Similar to males, female BTBR ob/ob mice display robust DPN, and pathways related to inflammation are dysregulated in peripheral nerve.
Collapse
Affiliation(s)
- Phillipe D O'Brien
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Junguk Hur
- Department of Basic Sciences, University of North Dakota, Grand Forks, ND 58203, USA
| | - Nicholas J Robell
- Department of Emergency Medicine, Henry Ford Hospital, Detroit, MI 48202, USA
| | - John M Hayes
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Stacey A Sakowski
- A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA.
| |
Collapse
|
20
|
Figueroa-Romero C, Hur J, Lunn JS, Paez-Colasante X, Bender DE, Yung R, Sakowski SA, Feldman EL. Expression of microRNAs in human post-mortem amyotrophic lateral sclerosis spinal cords provides insight into disease mechanisms. Mol Cell Neurosci 2015; 71:34-45. [PMID: 26704906 DOI: 10.1016/j.mcn.2015.12.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 11/23/2015] [Accepted: 12/14/2015] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis is a late-onset and terminal neurodegenerative disease. The majority of cases are sporadic with unknown causes and only a small number of cases are genetically linked. Recent evidence suggests that post-transcriptional regulation and epigenetic mechanisms, such as microRNAs, underlie the onset and progression of neurodegenerative disorders; therefore, altered microRNA expression may result in the dysregulation of key genes and biological pathways that contribute to the development of sporadic amyotrophic lateral sclerosis. Using systems biology analyses on postmortem human spinal cord tissue, we identified dysregulated mature microRNAs and their potential targets previously implicated in functional process and pathways associated with the pathogenesis of ALS. Furthermore, we report a global reduction of mature microRNAs, alterations in microRNA processing, and support for a role of the nucleotide binding protein, TAR DNA binding protein 43, in regulating sporadic amyotrophic lateral sclerosis-associated microRNAs, thereby offering a potential underlying mechanism for sporadic amyotrophic lateral sclerosis.
Collapse
Affiliation(s)
| | - Junguk Hur
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| | - J Simon Lunn
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| | | | - Diane E Bender
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| | - Raymond Yung
- Division of Geriatrics and Palliative Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA.,Geriatric Research, Education and Clinical Care Center, VA Ann Arbor Health System, Ann Arbor, MI 48105, USA
| | - Stacey A Sakowski
- A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA.,A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, MI 48109, USA
| |
Collapse
|
21
|
Paez-Colasante X, Figueroa-Romero C, Sakowski SA, Goutman SA, Feldman EL. Amyotrophic lateral sclerosis: mechanisms and therapeutics in the epigenomic era. Nat Rev Neurol 2015; 11:266-79. [PMID: 25896087 DOI: 10.1038/nrneurol.2015.57] [Citation(s) in RCA: 157] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of the motor neurons, which results in weakness and atrophy of voluntary skeletal muscles. Treatments do not modify the disease trajectory effectively, and only modestly improve survival. A complex interaction between genes, environmental exposure and impaired molecular pathways contributes to pathology in patients with ALS. Epigenetic mechanisms control the hereditary and reversible regulation of gene expression without altering the basic genetic code. Aberrant epigenetic patterns-including abnormal microRNA (miRNA) biogenesis and function, DNA modifications, histone remodeling, and RNA editing-are acquired throughout life and are influenced by environmental factors. Thus, understanding the molecular processes that lead to epigenetic dysregulation in patients with ALS might facilitate the discovery of novel therapeutic targets and biomarkers that could reduce diagnostic delay. These achievements could prove crucial for successful disease modification in patients with ALS. We review the latest findings regarding the role of miRNA modifications and other epigenetic mechanisms in ALS, and discuss their potential as therapeutic targets.
Collapse
Affiliation(s)
- Ximena Paez-Colasante
- Department of Neurology, University of Michigan, 1500 East Medical Centre Drive, 1914 Taubman Centre SPC 5316, Ann Arbor, MI 48109, USA
| | - Claudia Figueroa-Romero
- Department of Neurology, University of Michigan, 1500 East Medical Centre Drive, 1914 Taubman Centre SPC 5316, Ann Arbor, MI 48109, USA
| | - Stacey A Sakowski
- The A. Alfred Taubman Medical Research Institute, University of Michigan, 109 Zina Pitcher Place, 5017 A. Alfred Taubman Biomedical Science Research Building, Ann Arbor, MI 48109, USA
| | - Stephen A Goutman
- Department of Neurology, University of Michigan, 1500 East Medical Centre Drive, 1914 Taubman Centre SPC 5316, Ann Arbor, MI 48109, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, 1500 East Medical Centre Drive, 1914 Taubman Centre SPC 5316, Ann Arbor, MI 48109, USA
| |
Collapse
|
22
|
Sakowski SA, Feldman EL. The Spectrum of Motor Neuron Diseases: From Childhood Spinal Muscular Atrophy to Adult Amyotrophic Lateral Sclerosis. Neurotherapeutics 2015; 12:287-9. [PMID: 25794940 PMCID: PMC4404463 DOI: 10.1007/s13311-015-0349-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Stacey A. Sakowski
- />A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, MI 48109 USA
| | - Eva L. Feldman
- />A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, MI 48109 USA
- />Department of Neurology, University of Michigan, 109 Zina Pitcher Place, 5017 AAT-BSRB, Ann Arbor, MI 48109 USA
| |
Collapse
|
23
|
Kashlan ON, Kashlan BN, Oh SS, McGinley LM, Chen KS, Kupfer R, Erman A, Sakowski SA, Feldman EL. Histological Bulbar Manifestations in the ALS Rat. NEURODEGENER DIS 2015; 15:121-6. [PMID: 25825172 DOI: 10.1159/000377725] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 02/04/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Almost all patients with amyotrophic lateral sclerosis (ALS) develop bulbar symptoms; therefore, it is important to have valid animal models that accurately reflect these features. While the SOD1-G93A rat is extensively used as an ALS model, bulbar symptoms in this model are not well characterized. OBJECTIVE In the present study, we aimed to better characterize bulbar dysfunction in terms of histology to determine whether the SOD1-G93A rat is a useful model for bulbar-onset ALS. METHODS Sixty-day-old SOD1-G93A rats on a Sprague-Dawley background and age-matched wild-type controls were assessed weekly for global motor function, facial nerve function, and vagal nerve function. The study endpoint was determined when an SOD1-G93A rat could not right itself within 30 s of being placed on its side. At that point, neuronal counts were assessed in different brainstem cranial nerve nuclei. In addition, the masseter muscle, posterior belly of the digastric muscle, and tongue muscle were evaluated for intact neuromuscular junctions. RESULTS Our data demonstrate decreases in the number of motor neurons in the trigeminal, facial, and hypoglossal nuclei, as well as compromised neuromuscular junction integrity in the muscles they innervate. CONCLUSION These findings suggest that, from a histological standpoint, the SOD1-G93A rat is a valid model of ALS bulbar symptoms.
Collapse
Affiliation(s)
- Osama N Kashlan
- Department of Neurosurgery, University of Michigan, Ann Arbor, Mich., USA
| | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Abstract
Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes and is associated with significant morbidity and mortality. DPN is characterized by progressive, distal-to-proximal degeneration of peripheral nerves that leads to pain, weakness, and eventual loss of sensation. The mechanisms underlying DPN pathogenesis are uncertain, and other than tight glycemic control in type 1 patients, there is no effective treatment. Mouse models of type 1 (T1DM) and type 2 diabetes (T2DM) are critical to improving our understanding of DPN pathophysiology and developing novel treatment strategies. In this review, we discuss the most widely used T1DM and T2DM mouse models for DPN research, with emphasis on the main neurologic phenotype of each model. We also discuss important considerations for selecting appropriate models for T1DM and T2DM DPN studies and describe the promise of novel emerging diabetic mouse models for DPN research. The development, characterization, and comprehensive neurologic phenotyping of clinically relevant mouse models for T1DM and T2DM will provide valuable resources for future studies examining DPN pathogenesis and novel therapeutic strategies.
Collapse
|
25
|
O'Brien PD, Hur J, Hayes JM, Backus C, Sakowski SA, Feldman EL. BTBR ob/ob mice as a novel diabetic neuropathy model: Neurological characterization and gene expression analyses. Neurobiol Dis 2015; 73:348-55. [PMID: 25447227 PMCID: PMC4416075 DOI: 10.1016/j.nbd.2014.10.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 10/17/2014] [Accepted: 10/22/2014] [Indexed: 12/25/2022] Open
Abstract
Given the lack of treatments for diabetic neuropathy (DN), a common diabetic complication, accurate disease models are necessary. Characterization of the leptin-deficient BTBR ob/ob mouse, a type 2 diabetes model, demonstrated that the mice develop robust diabetes coincident with severe neuropathic features, including nerve conduction deficits and intraepidermal nerve fiber loss by 9 and 13 weeks of age, respectively, supporting its use as a DN model. To gain insight into DN mechanisms, we performed microarray analysis on sciatic nerve from BTBR ob/ob mice, identifying 1503 and 642 differentially expressed genes associated with diabetes at 5 and 13 weeks, respectively. Further analyses identified overrepresentation of inflammation and immune-related functions in BTBR ob/ob mice, which interestingly were more highly represented at 5 weeks, an observation that may suggest a contributory role in DN onset. To complement the gene expression analysis, we demonstrated that protein levels of select cytokines were significantly upregulated at 13 weeks in BTBR ob/ob mouse sciatic nerve. Furthermore, we compared our array data to that from an established DN model, the C57BKS db/db mouse, which reflected a common dysregulation of inflammatory and immune-related pathways. Together, our data demonstrate that BTBR ob/ob mice develop rapid and robust DN associated with dysregulated inflammation and immune-related processes.
Collapse
Affiliation(s)
- Phillipe D O'Brien
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Junguk Hur
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - John M Hayes
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Carey Backus
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Stacey A Sakowski
- A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, MI 48109, USA.
| |
Collapse
|
26
|
Lunn JS, Sakowski SA, Feldman EL. Concise review: Stem cell therapies for amyotrophic lateral sclerosis: recent advances and prospects for the future. Stem Cells 2014; 32:1099-109. [PMID: 24448926 DOI: 10.1002/stem.1628] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 12/12/2013] [Accepted: 12/14/2013] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a lethal disease involving the loss of motor neurons. Although the mechanisms responsible for motor neuron degeneration in ALS remain elusive, the development of stem cell-based therapies for the treatment of ALS has gained widespread support. Here, we review the types of stem cells being considered for therapeutic applications in ALS, and emphasize recent preclinical advances that provide supportive rationale for clinical translation. We also discuss early trials from around the world translating cellular therapies to ALS patients, and offer important considerations for future clinical trial design. Although clinical translation is still in its infancy, and additional insight into the mechanisms underlying therapeutic efficacy and the establishment of long-term safety are required, these studies represent an important first step toward the development of effective cellular therapies for the treatment of ALS.
Collapse
Affiliation(s)
- J Simon Lunn
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | | | | |
Collapse
|
27
|
Abstract
SIGNIFICANCE Diabetes and other diseases that comprise the metabolic syndrome have reached epidemic proportions. Diabetic peripheral neuropathy (DPN) is the most prevalent complication of diabetes, affecting ~50% of diabetic patients. Characterized by chronic pain or loss of sensation, recurrent foot ulcerations, and risk for amputation, DPN is associated with significant morbidity and mortality. Mechanisms underlying DPN pathogenesis are complex and not well understood, and no effective treatments are available. Thus, an improved understanding of DPN pathogenesis is critical for the development of successful therapeutic options. RECENT ADVANCES Recent research implicates endoplasmic reticulum (ER) stress as a novel mechanism in the onset and progression of DPN. ER stress activates the unfolded protein response (UPR), a well-orchestrated signaling cascade responsible for relieving stress and restoring normal ER function. CRITICAL ISSUES During times of extreme or chronic stress, such as that associated with diabetes, the UPR may be insufficient to alleviate ER stress, resulting in apoptosis. Here, we discuss the potential role of ER stress in DPN, as well as evidence demonstrating how ER stress intersects with pathways involved in DPN development and progression. An improved understanding of how ER stress contributes to peripheral nerve dysfunction in diabetes will provide important insight into DPN pathogenesis. FUTURE DIRECTIONS Future studies aimed at gaining the necessary insight into ER stress in DPN pathogenesis will ultimately facilitate the development of novel therapies.
Collapse
|
28
|
Feldman EL, Boulis NM, Hur J, Johe K, Rutkove SB, Federici T, Polak M, Bordeau J, Sakowski SA, Glass JD. Intraspinal neural stem cell transplantation in amyotrophic lateral sclerosis: phase 1 trial outcomes. Ann Neurol 2014; 75:363-73. [PMID: 24510776 PMCID: PMC4005820 DOI: 10.1002/ana.24113] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 01/17/2014] [Accepted: 01/25/2014] [Indexed: 12/14/2022]
Abstract
Objective The US Food and Drug Administration–approved trial, “A Phase 1, Open-Label, First-in-Human, Feasibility and Safety Study of Human Spinal Cord-Derived Neural Stem Cell Transplantation for the Treatment of Amyotrophic Lateral Sclerosis, Protocol Number: NS2008-1,” is complete. Our overall objective was to assess the safety and feasibility of stem cell transplantation into lumbar and/or cervical spinal cord regions in amyotrophic lateral sclerosis (ALS) subjects. Methods Preliminary results have been reported on the initial trial cohort of 12 ALS subjects. Here, we describe the safety and functional outcome monitoring results for the final trial cohort, consisting of 6 ALS subjects receiving 5 unilateral cervical intraspinal neural stem cell injections. Three of these subjects previously received 10 total bilateral lumbar injections as part of the earlier trial cohort. All injections utilized a novel spinal-mounted stabilization and injection device to deliver 100,000 neural stem cells per injection, for a dosing range up to 1.5 million cells. Subject assessments included detailed pre- and postsurgical neurological outcome measures. Results The cervical injection procedure was well tolerated and disease progression did not accelerate in any subject, verifying the safety and feasibility of cervical and dual-targeting approaches. Analyses on outcome data revealed preliminary insight into potential windows of stem cell biological activity and identified clinical assessment measures that closely correlate with ALS Functional Rating Scale-Revised scores, a standard assessment for ALS clinical trials. Interpretation This is the first report of cervical and dual-targeted intraspinal transplantation of neural stem cells in ALS subjects. This approach is feasible and well-tolerated, supporting future trial phases examining therapeutic dosing and efficacy.
Collapse
Affiliation(s)
- Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI
| | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Sakowski SA, Lunn JS, Busta AS, Oh SS, Zamora-Berridi G, Palmer M, Rosenberg AA, Philip SG, Dowling JJ, Feldman EL. Neuromuscular effects of G93A-SOD1 expression in zebrafish. Mol Neurodegener 2012; 7:44. [PMID: 22938571 PMCID: PMC3506515 DOI: 10.1186/1750-1326-7-44] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 08/26/2012] [Indexed: 12/11/2022] Open
Abstract
Background Amyotrophic lateral sclerosis (ALS) is a fatal disorder involving the degeneration and loss of motor neurons. The mechanisms of motor neuron loss in ALS are unknown and there are no effective treatments. Defects in the distal axon and at the neuromuscular junction are early events in the disease course, and zebrafish provide a promising in vivo system to examine cellular mechanisms and treatments for these events in ALS pathogenesis. Results We demonstrate that transient genetic manipulation of zebrafish to express G93A-SOD1, a mutation associated with familial ALS, results in early defects in motor neuron outgrowth and axonal branching. This is consistent with previous reports on motor neuron axonal defects associated with familial ALS genes following knockdown or mutant protein overexpression. We also demonstrate that upregulation of growth factor signaling is capable of rescuing these early defects, validating the potential of the model for therapeutic discovery. We generated stable transgenic zebrafish lines expressing G93A-SOD1 to further characterize the consequences of G93A-SOD1 expression on neuromuscular pathology and disease progression. Behavioral monitoring reveals evidence of motor dysfunction and decreased activity in transgenic ALS zebrafish. Examination of neuromuscular and neuronal pathology throughout the disease course reveals a loss of neuromuscular junctions and alterations in motor neuron innervations patterns with disease progression. Finally, motor neuron cell loss is evident later in the disease. Conclusions This sequence of events reflects the stepwise mechanisms of degeneration in ALS, and provides a novel model for mechanistic discovery and therapeutic development for neuromuscular degeneration in ALS.
Collapse
Affiliation(s)
- Stacey A Sakowski
- Department of Neurology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor 5017 AAT-BSRBMI, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Abstract
Insulin-like growth factors (IGFs) play an integral role in development, growth, and survival. This article details the current understanding of the effects of IGFs in the peripheral nervous system (PNS) during health and disease, and introduces how the IGF system regulates PNS development and impacts growth and survival of PNS cells. Also discussed are implications of IGF signaling in neurodegeneration and the status and prospects of IGF therapies for PNS conditions. There is substantial support for the application of IGF therapies in the treatment of PNS injury and disease.
Collapse
Affiliation(s)
- Stacey A Sakowski
- A. Alfred Taubman Medical Research Institute, University of Michigan, 109 Zina Pitcher Place, 4019 AAT-BSRB, Ann Arbor, MI 48109, USA
| | | |
Collapse
|
31
|
Oh SS, Sullivan KA, Wilkinson JE, Backus C, Hayes JM, Sakowski SA, Feldman EL. Neurodegeneration and early lethality in superoxide dismutase 2-deficient mice: a comprehensive analysis of the central and peripheral nervous systems. Neuroscience 2012; 212:201-13. [PMID: 22516022 DOI: 10.1016/j.neuroscience.2012.03.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 03/02/2012] [Accepted: 03/20/2012] [Indexed: 01/17/2023]
Abstract
The contribution of oxidative stress to diabetic complications including neuropathy is widely known. Mitochondrial and cellular damage are associated with the overproduction of reactive oxygen species and decreased levels or function of the cellular antioxidant mitochondrial manganese superoxide dismutase (SOD2). We hypothesized that targeted SOD2 deletion in the peripheral nervous system using cre-lox technology under control of the nestin promoter would accelerate neuropathy in a type 2 model of diabetes, the BKS.db/db mouse. SOD2-deficient mice, however, demonstrated severe gait deformities and seizures and died by 20 days of age. Examination of SOD2 expression levels revealed that SOD2 was lost in brain and reduced in the spinal cord, but appeared normal in dorsal root ganglia and peripheral nerves in SOD2-deficient mice. These findings indicate incomplete targeted knockout of SOD2. Morphological examination revealed cortical lesions similar to spongiform encephalopathy in the brain of SOD2-deficient mice. No lesions were evident in the spinal cord, but changes in myelin within the sciatic and sural nerves including a lack of cohesion between layers of compact myelin were observed. Together, these results indicate that targeted neuronal SOD2 knockout using the nestin promoter results in severe central nervous system degeneration and perinatal lethality in mice. A specific peripheral nervous system-targeting construct is required to examine the consequences of SOD2 knockout in diabetic neuropathy.
Collapse
Affiliation(s)
- S S Oh
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | | | | | | | | | | | | |
Collapse
|
32
|
Roberts SF, Fischhoff MA, Sakowski SA, Feldman EL. Perspective: Transforming science into medicine: how clinician-scientists can build bridges across research's "valley of death". Acad Med 2012; 87:266-270. [PMID: 22373616 DOI: 10.1097/acm.0b013e3182446fa3] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Significant increases in National Institutes of Health (NIH) spending on medical research have not produced corresponding increases in new treatments and cures. Instead, laboratory discoveries remain in what has been termed the "valley of death," the gap between bench research and clinical application. Recently, there has been considerable discussion in the literature and scientific community about the causes of this phenomenon and how to bridge the abyss. In this article, the authors examine one possible explanation: Clinician-scientists' declining role in the medical research enterprise has had a dilatory effect on the successful translation of laboratory breakthroughs into new clinical applications. In recent decades, the percentage of MDs receiving NIH funding has drastically decreased compared with PhDs. The growing gap between the research and clinical enterprises has resulted in fewer scientists with a true understanding of clinical problems as well as scientists who are unable to or uninterested in gleaning new basic research hypotheses from failed clinical trials. The NIH and many U.S. medical schools have recognized the decline of the clinician-scientist as a major problem and adopted innovative programs to reverse the trend. However, more radical action may be required, including major changes to the NIH peer-review process, greater funding for translational research, and significantly more resources for the training, debt relief, and early career support of potential clinician-scientists. Such improvements are required for clinician-scientists to conduct translational research that bridges the valley of death and transforms biomedical research discoveries into tangible clinical treatments and technologies.
Collapse
|
33
|
Sakowski SA, Lunn JS, Busta AS, Palmer M, Dowling JJ, Feldman EL. A novel approach to study motor neurons from zebrafish embryos and larvae in culture. J Neurosci Methods 2012; 205:277-82. [PMID: 22285259 DOI: 10.1016/j.jneumeth.2012.01.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 01/11/2012] [Accepted: 01/11/2012] [Indexed: 12/27/2022]
Abstract
Zebrafish are becoming increasingly popular models for examining the mechanisms of and treatments for neurological diseases. The available methods and technology to examine disease processes in vivo are increasing, however, detailed observations of subcellular structures and processes are complex in whole organisms. To address this need, we developed a primary motor neuron (MN) culture technique for utilization with zebrafish neurological disease models. Our protocol enables the culturing of cells from embryos older than 24h post-fertilization, at points after MN axonal development and outgrowth begins, which enables MN axons to develop in vivo in the context of the normal endogenous cues of the model organism, while also providing the accessibility of an in vitro system. When utilized with the increasing number of genetically modified or transgenic models of neurological diseases, this approach provides a novel tool for the examination of cellular and subcellular disease mechanisms, and offers a new platform for therapeutic discoveries in zebrafish.
Collapse
|
34
|
Abstract
Over the past 20 years, stem cell technologies have become an increasingly attractive option to investigate and treat neurodegenerative diseases. In the current review, we discuss the process of extending basic stem cell research into translational therapies for patients suffering from neurodegenerative diseases. We begin with a discussion of the burden of these diseases on society, emphasizing the need for increased attention toward advancing stem cell therapies. We then explain the various types of stem cells utilized in neurodegenerative disease research, and outline important issues to consider in the transition of stem cell therapy from bench to bedside. Finally, we detail the current progress regarding the applications of stem cell therapies to specific neurodegenerative diseases, focusing on Parkinson disease, Huntington disease, Alzheimer disease, amyotrophic lateral sclerosis, and spinal muscular atrophy. With a greater understanding of the capacity of stem cell technologies, there is growing public hope that stem cell therapies will continue to progress into realistic and efficacious treatments for neurodegenerative diseases.
Collapse
Affiliation(s)
- J Simon Lunn
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | | | | | | |
Collapse
|
35
|
Lunn JS, Sakowski SA, Federici T, Glass JD, Boulis NM, Feldman EL. Stem cell technology for the study and treatment of motor neuron diseases. Regen Med 2011; 6:201-13. [PMID: 21391854 DOI: 10.2217/rme.11.6] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis and spinal muscular atrophy are devastating neurodegenerative diseases that lead to the specific loss of motor neurons. Recently, stem cell technologies have been developed for the investigation and treatment of both diseases. Here we discuss the different stem cells currently being studied for mechanistic discovery and therapeutic development, including embryonic, adult and induced pluripotent stem cells. We also present supporting evidence for the utilization of stem cell technology in the treatment of amyotrophic lateral sclerosis and spinal muscular atrophy, and describe key issues that must be considered for the transition of stem cell therapies for motor neuron diseases from bench to bedside. Finally, we discuss the first-in-human Phase I trial currently underway examining the safety and feasibility of intraspinal stem cell injections in amyotrophic lateral sclerosis patients as a foundation for translating stem cell therapies for various neurological diseases.
Collapse
Affiliation(s)
- J Simon Lunn
- University of Michigan Department of Neurology, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | | | | | | | | | | |
Collapse
|
36
|
Sakowski SA, Heavener SB, Lunn JS, Fung K, Oh SS, Spratt SK, Hogikyan ND, Feldman EL. Neuroprotection using gene therapy to induce vascular endothelial growth factor-A expression. Gene Ther 2009; 16:1292-9. [PMID: 19727131 PMCID: PMC4215171 DOI: 10.1038/gt.2009.111] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Revised: 07/31/2009] [Accepted: 08/01/2009] [Indexed: 01/19/2023]
Abstract
Engineered zinc-finger protein (ZFP) transcription factors induce the expression of endogenous genes and can be remotely delivered using adenoviral vectors. One such factor, Ad-32Ep65-Flag (Ad-p65), targets and induces expression of vascular endothelial growth factor (VEGF; also called VEGF-A) splice variants in their normal biological stoichiometry. We show that Ad-p65 transfection of primary motor neurons results in VEGF variant expression and a significant increase in axon outgrowth in these cells. Given the neuroprotective effects of VEGF and its ability to increase neurite outgrowth, we examined the efficacy of Ad-p65 to enhance motor neuron regeneration in vivo using rats that have undergone recurrent laryngeal nerve (RLN)-crush injury. Injection of Ad-p65 after RLN crush accelerated the return of vocal fold mobility and the percentage of nerve-endplate contacts in the thyroarytenoid muscle. Overall, adenoviral delivery of an engineered ZFP transcription factor inducing VEGF-A splice variant expression enhances nerve regeneration. ZFP transcription factor gene therapy to increase expression of the full complement of VEGF-A splice variants is a promising avenue for the treatment of nerve injury and neurodegeneration.
Collapse
Affiliation(s)
- Stacey A. Sakowski
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - S. Brett Heavener
- Department of Otolaryngology-Head and Neck Surgery, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - J. Simon Lunn
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - Kevin Fung
- Department of Otolaryngology, University of Western Ontario, London, Ontario, Canada
| | - Sang Su Oh
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, MI, USA
| | | | - Norman D. Hogikyan
- Department of Otolaryngology-Head and Neck Surgery, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - Eva L. Feldman
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, MI, USA
| |
Collapse
|
37
|
Abstract
Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disorder characterized by selective loss of motor neurons (MNs). Twenty percent of familial ALS cases are associated with mutations in Cu(2+)/Zn(2+) superoxide dismutase (SOD1). To specifically understand the cellular mechanisms underlying mutant SOD1 toxicity, we have established an in vitro model of ALS using rat primary MN cultures transfected with an adenoviral vector encoding a mutant SOD1, G93A-SOD1. Transfected cells undergo axonal degeneration and alterations in biochemical responses characteristic of cell death such as activation of caspase-3. Vascular endothelial growth factor (VEGF) is an angiogenic and neuroprotective growth factor that can increase axonal outgrowth, block neuronal apoptosis, and promote neurogenesis. Decreased VEGF gene expression in mice results in a phenotype similar to that seen in patients with ALS, thus linking loss of VEGF to the pathogenesis of MN degeneration. Decreased neurotrophic signals prior to and during disease progression may increase MN susceptibility to mutant SOD1-induced toxicity. In this study, we demonstrate a decrease in VEGF and VEGFR2 levels in the spinal cord of G93A-SOD1 ALS mice. Furthermore, in isolated MN cultures, VEGF alleviates the effects of G93A-SOD1 toxicity and neuroprotection involves phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling. Overall, these studies validate the usefulness of VEGF as a potential therapeutic factor for the treatment of ALS and give valuable insight into the responsible signaling pathways and mechanisms involved.
Collapse
Affiliation(s)
- J. Simon Lunn
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Stacey A. Sakowski
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Bhumsoo Kim
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Eva L. Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| |
Collapse
|
38
|
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects both upper and lower motorneurons (MN) resulting in weakness, paralysis and subsequent death. Insulin-like growth factor-I (IGF-I) is a potent neurotrophic factor that has neuroprotective properties in the central and peripheral nervous systems. Due to the efficacy of IGF-I in the treatment of other diseases and its ability to promote neuronal survival, IGF-I is being extensively studied in ALS therapeutic trials. This review covers in vitro and in vivo studies examining the efficacy of IGF-I in ALS model systems and also addresses the mechanisms by which IGF-I asserts its effects in these models, the status of the IGF-I system in ALS patients, results of clinical trials, and the need for the development of better delivery mechanisms to maximize IGF-I efficacy. The knowledge obtained from these studies suggests that IGF-I has the potential to be a safe and efficacious therapy for ALS.
Collapse
Affiliation(s)
- Stacey A Sakowski
- Department of Neurology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | | | | |
Collapse
|
39
|
Kuhn DM, Sakowski SA, Geddes TJ, Wilkerson C, Haycock JW. Phosphorylation and activation of tryptophan hydroxylase 2: identification of serine-19 as the substrate site for calcium, calmodulin-dependent protein kinase II. J Neurochem 2007; 103:1567-73. [PMID: 17727633 DOI: 10.1111/j.1471-4159.2007.04855.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tryptophan hydroxylase (TPH) is the initial and rate-limiting enzyme in the biosynthesis of serotonin. TPH was once thought to be a single-gene product but it is now known to exist in two isoforms. TPH1 is found in the periphery and pineal gland whereas TPH2 is expressed specifically in the CNS. Both TPH isoforms are known to be regulated by protein kinase-dependent phosphorylation and the sites of modification of TPH1 by protein kinase A have been identified. While TPH2 is activated by calcium, calmodulin-dependent protein kinase II (CaMKII), the sites at which this isoform is modified are not known. Treatment of wild-type TPH2 with CaMKII followed by mass spectrometry analysis revealed that the enzyme was activated and phosphorylated at a single site, serine-19. Mutagenesis of serine-19 to alanine did not alter the catalytic function of TPH2 but this mutant enzyme was neither activated nor phosphorylated by CaMKII. A phosphopeptide bracketing phosphoserine-19 in TPH2 was used as an antigen to generate polyclonal antibodies against phosphoserine-19. The antibodies are highly specific for phosphoserine-19 in TPH2. The antibodies do not react with wild-type TPH2 or TPH1 and they do not recognize phophoserine-58 or phosphoserine-260 in TPH1. These results establish that activation of TPH2 by CaMKII is mediated by phosphorylation of serine-19 within the regulatory domain of the enzyme. Production of a specific antibody against the CaMKII phosphorylation site in TPH2 represents a valuable tool to advance the study of the mechanisms regulating the function of this important enzyme.
Collapse
Affiliation(s)
- Donald M Kuhn
- Department of Psychiatry & Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan, USA.
| | | | | | | | | |
Collapse
|
40
|
Sakowski SA, Geddes TJ, Thomas DM, Levi E, Hatfield JS, Kuhn DM. Differential tissue distribution of tryptophan hydroxylase isoforms 1 and 2 as revealed with monospecific antibodies. Brain Res 2006; 1085:11-8. [PMID: 16581041 DOI: 10.1016/j.brainres.2006.02.047] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 02/07/2006] [Accepted: 02/13/2006] [Indexed: 11/15/2022]
Abstract
Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of the neurotransmitter serotonin. Once thought to be a single-gene product, TPH is now known to exist in two isoforms-TPH1 is found in the pineal and gut, and TPH2 is selectively expressed in brain. Heretofore, probes used for localization of TPH protein or mRNA could not distinguish between the TPH isoforms because of extensive homology shared by them at the nucleotide and amino acid level. We have produced monospecific polyclonal antibodies against TPH1 and TPH2 using peptide antigens from nonoverlapping sequences in the respective proteins. These antibodies allow the differentiation of TPH1 and TPH2 upon immunoblotting, immunoprecipitation, and immunocytochemical staining of tissue sections from brain and gut. TPH1 and TPH2 antibodies do not cross-react with either tyrosine hydroxylase or phenylalanine hydroxylase. Analysis of mouse tissues confirms that TPH1 is the predominant form expressed in pineal gland and in P815 mastocytoma cells with a molecular weight of 51 kDa. TPH2 is the predominant enzyme form expressed in brain extracts from mesencephalic tegmentum, striatum, and hippocampus with a molecular weight of 56 kDa. Antibody specificity against TPH1 and TPH2 is retained across mouse, rat, rabbit, primate, and human tissues. Antibodies that distinguish between the isoforms of TPH will allow studies of the differential regulation of their expression in brain and periphery.
Collapse
Affiliation(s)
- Stacey A Sakowski
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA
| | | | | | | | | | | |
Collapse
|
41
|
Abstract
Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of the neurotransmitter serotonin (5-HT). Once thought to be a single gene product, TPH is now known to exist in two isoforms. Isoform 1 (TPH1) is found in the pineal gland and gut, and isoform 2 (TPH2) is selectively expressed in brain. A single-nucleotide polymorphism in TPH2 results in a proline-to-arginine mutation at residue 447 and substantially lowers catalytic activity. In view of the importance of TPH in determining brain 5-HT function, we cloned TPH2 and produced the P447R mutant to assess the importance of this proline in enzyme function. Catalytically active TPH2 and the P447R mutant were expressed at the predicted subunit molecular mass of 56 kDa. The P447R mutant expressed less than 50% of the activity of TPH2. Mutation of this conserved proline in TPH1 (P403R) also resulted in an enzyme with significantly lower activity than the wild-type enzyme. The P447R mutant had a V(max) 50% lower than that of TPH2. The P447R mutation did not alter the oligomeric assembly of the protein, nor change its responsiveness to cysteine modification. The P447R mutation did not alter enzyme substrate specificity or stability, but conferred slightly enhanced sensitivity to inhibition by dopamine and diminished sensitivity to iron in catalysis. The conserved proline in TPH (residue 447 in TPH2 and 403 in TPH1) plays an important role in enzyme function by regulating V(max) of the catalytic reaction.
Collapse
Affiliation(s)
- Stacey A Sakowski
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI, USA
| | | | | |
Collapse
|
42
|
Kuhn DM, Sakowski SA, Sadidi M, Geddes TJ. Nitrotyrosine as a marker for peroxynitrite-induced neurotoxicity: the beginning or the end of the end of dopamine neurons? J Neurochem 2004; 89:529-36. [PMID: 15086510 DOI: 10.1111/j.1471-4159.2004.02346.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This review examines the involvement of nitrotyrosine as a marker for peroxynitrite-mediated damage in the dopamine neuronal system. We propose that the dopamine neuronal phenotype can influence the cytotoxic signature of peroxynitrite. Dopamine and tetrahydrobiopterin are concentrated in dopamine neurons, and both are essential for their proper neurochemical function. It is not well appreciated that dopamine and tetrahydrobiopterin are also powerful blockers of peroxynitrite-induced tyrosine nitration. What is more, the reaction of peroxynitrite with either dopamine or tetrahydrobiopterin forms chemical species (i.e. o-quinones and pterin radicals, respectively) whose cytotoxic effects may be manifested far earlier than nitrotyrosine formation in the course of dopamine neuronal damage. A better understanding of how the dopamine neuronal phenotype modulates the effects of reactive nitrogen species could reveal early steps in drug- and disease-induced damage to the dopamine neuron and form the basis for rational, protective therapies.
Collapse
Affiliation(s)
- Donald M Kuhn
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan, USA.
| | | | | | | |
Collapse
|